Mach number (M) is the ratio of an object's speed to the speed of sound in the surrounding medium. M = v / c, where v is the object's velocity and c is the local speed of sound. It is dimensionless.

What are the flight regimes?

Subsonic: M < 0.8; Transonic: 0.8 ≤ M < 1.2; Supersonic: 1.2 ≤ M < 5; Hypersonic: M ≥ 5. These boundaries are approximate and vary by application.

How does temperature affect the speed of sound in air?

In air, the speed of sound is approximately c = 331.3 × √(1 + T/273.15) m/s, where T is temperature in Celsius. Higher temperatures increase the speed of sound.

Does this work for fluids other than air?

Yes. Enter the known speed of sound for any fluid (water, helium, etc.) directly in the "Speed of Sound" mode. The Mach number formula is the same regardless of medium.

What is Mach 1 in km/h at sea level?

At sea level (15 °C), the speed of sound is about 340.3 m/s, which equals approximately 1,225 km/h or 761 mph.

Mach Number Calculator

Enter object velocity and speed of sound (or air temperature) to instantly calculate Mach number and flight regime.

Inputs

Speed of sound source

Object velocity

Speed of sound

Result

Enter values and click Calculate.

Flight Regime Reference

Regime	Mach Range	Examples
Subsonic	M < 0.8	Commercial airliners, propeller aircraft
Transonic	0.8 ≤ M < 1.2	Modern jet fighters at cruise, some airliners
Supersonic	1.2 ≤ M < 5	Concorde (M 2), SR-71 (M 3.3), rifle bullets
Hypersonic	M ≥ 5	Space shuttle re-entry (M 25), ICBMs

Copied!

Summary

Enter object velocity and speed of sound (or air temperature) to instantly calculate Mach number and flight regime.

How it works

Choose your input mode: provide the speed of sound directly, or let the tool compute it from air temperature.
Enter the object's velocity in your preferred unit (m/s, km/h, mph, or ft/s).
If using temperature mode, enter the ambient air temperature in °C, °F, or K.
The tool divides velocity by speed of sound to compute the Mach number.
Read the result along with the flight regime label (subsonic, transonic, supersonic, or hypersonic).

Use cases

Estimate the Mach number of a commercial aircraft at cruise altitude.
Check whether a projectile or rocket exceeds the sound barrier.
Understand aerodynamic regimes in aerospace engineering coursework.
Convert a known airspeed to Mach for flight planning or simulation.
Explore how temperature changes affect the speed of sound in air.
Verify hand calculations for fluid mechanics homework problems.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu